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f3b44f92 JA |
1 | // SPDX-License-Identifier: GPL-2.0 |
2 | #include <linux/kernel.h> | |
3 | #include <linux/errno.h> | |
4 | #include <linux/fs.h> | |
5 | #include <linux/file.h> | |
6 | #include <linux/blk-mq.h> | |
7 | #include <linux/mm.h> | |
8 | #include <linux/slab.h> | |
9 | #include <linux/fsnotify.h> | |
10 | #include <linux/poll.h> | |
11 | #include <linux/nospec.h> | |
12 | #include <linux/compat.h> | |
13 | #include <linux/io_uring.h> | |
14 | ||
15 | #include <uapi/linux/io_uring.h> | |
16 | ||
f3b44f92 JA |
17 | #include "io_uring.h" |
18 | #include "opdef.h" | |
19 | #include "kbuf.h" | |
20 | #include "rsrc.h" | |
21 | #include "rw.h" | |
22 | ||
23 | struct io_rw { | |
24 | /* NOTE: kiocb has the file as the first member, so don't do it here */ | |
25 | struct kiocb kiocb; | |
26 | u64 addr; | |
27 | u32 len; | |
28 | rwf_t flags; | |
29 | }; | |
30 | ||
31 | static inline bool io_file_supports_nowait(struct io_kiocb *req) | |
32 | { | |
33 | return req->flags & REQ_F_SUPPORT_NOWAIT; | |
34 | } | |
35 | ||
36 | int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe) | |
37 | { | |
f2ccb5ae | 38 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
f3b44f92 JA |
39 | unsigned ioprio; |
40 | int ret; | |
41 | ||
42 | rw->kiocb.ki_pos = READ_ONCE(sqe->off); | |
43 | /* used for fixed read/write too - just read unconditionally */ | |
44 | req->buf_index = READ_ONCE(sqe->buf_index); | |
45 | ||
46 | if (req->opcode == IORING_OP_READ_FIXED || | |
47 | req->opcode == IORING_OP_WRITE_FIXED) { | |
48 | struct io_ring_ctx *ctx = req->ctx; | |
49 | u16 index; | |
50 | ||
51 | if (unlikely(req->buf_index >= ctx->nr_user_bufs)) | |
52 | return -EFAULT; | |
53 | index = array_index_nospec(req->buf_index, ctx->nr_user_bufs); | |
54 | req->imu = ctx->user_bufs[index]; | |
55 | io_req_set_rsrc_node(req, ctx, 0); | |
56 | } | |
57 | ||
58 | ioprio = READ_ONCE(sqe->ioprio); | |
59 | if (ioprio) { | |
60 | ret = ioprio_check_cap(ioprio); | |
61 | if (ret) | |
62 | return ret; | |
63 | ||
64 | rw->kiocb.ki_ioprio = ioprio; | |
65 | } else { | |
66 | rw->kiocb.ki_ioprio = get_current_ioprio(); | |
67 | } | |
68 | ||
69 | rw->addr = READ_ONCE(sqe->addr); | |
70 | rw->len = READ_ONCE(sqe->len); | |
71 | rw->flags = READ_ONCE(sqe->rw_flags); | |
72 | return 0; | |
73 | } | |
74 | ||
75 | void io_readv_writev_cleanup(struct io_kiocb *req) | |
76 | { | |
77 | struct io_async_rw *io = req->async_data; | |
78 | ||
79 | kfree(io->free_iovec); | |
80 | } | |
81 | ||
82 | static inline void io_rw_done(struct kiocb *kiocb, ssize_t ret) | |
83 | { | |
84 | switch (ret) { | |
85 | case -EIOCBQUEUED: | |
86 | break; | |
87 | case -ERESTARTSYS: | |
88 | case -ERESTARTNOINTR: | |
89 | case -ERESTARTNOHAND: | |
90 | case -ERESTART_RESTARTBLOCK: | |
91 | /* | |
92 | * We can't just restart the syscall, since previously | |
93 | * submitted sqes may already be in progress. Just fail this | |
94 | * IO with EINTR. | |
95 | */ | |
96 | ret = -EINTR; | |
97 | fallthrough; | |
98 | default: | |
99 | kiocb->ki_complete(kiocb, ret); | |
100 | } | |
101 | } | |
102 | ||
103 | static inline loff_t *io_kiocb_update_pos(struct io_kiocb *req) | |
104 | { | |
f2ccb5ae | 105 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
f3b44f92 JA |
106 | |
107 | if (rw->kiocb.ki_pos != -1) | |
108 | return &rw->kiocb.ki_pos; | |
109 | ||
110 | if (!(req->file->f_mode & FMODE_STREAM)) { | |
111 | req->flags |= REQ_F_CUR_POS; | |
112 | rw->kiocb.ki_pos = req->file->f_pos; | |
113 | return &rw->kiocb.ki_pos; | |
114 | } | |
115 | ||
116 | rw->kiocb.ki_pos = 0; | |
117 | return NULL; | |
118 | } | |
119 | ||
120 | static void io_req_task_queue_reissue(struct io_kiocb *req) | |
121 | { | |
122 | req->io_task_work.func = io_queue_iowq; | |
123 | io_req_task_work_add(req); | |
124 | } | |
125 | ||
126 | #ifdef CONFIG_BLOCK | |
127 | static bool io_resubmit_prep(struct io_kiocb *req) | |
128 | { | |
129 | struct io_async_rw *io = req->async_data; | |
130 | ||
131 | if (!req_has_async_data(req)) | |
132 | return !io_req_prep_async(req); | |
133 | iov_iter_restore(&io->s.iter, &io->s.iter_state); | |
134 | return true; | |
135 | } | |
136 | ||
137 | static bool io_rw_should_reissue(struct io_kiocb *req) | |
138 | { | |
139 | umode_t mode = file_inode(req->file)->i_mode; | |
140 | struct io_ring_ctx *ctx = req->ctx; | |
141 | ||
142 | if (!S_ISBLK(mode) && !S_ISREG(mode)) | |
143 | return false; | |
144 | if ((req->flags & REQ_F_NOWAIT) || (io_wq_current_is_worker() && | |
145 | !(ctx->flags & IORING_SETUP_IOPOLL))) | |
146 | return false; | |
147 | /* | |
148 | * If ref is dying, we might be running poll reap from the exit work. | |
149 | * Don't attempt to reissue from that path, just let it fail with | |
150 | * -EAGAIN. | |
151 | */ | |
152 | if (percpu_ref_is_dying(&ctx->refs)) | |
153 | return false; | |
154 | /* | |
155 | * Play it safe and assume not safe to re-import and reissue if we're | |
156 | * not in the original thread group (or in task context). | |
157 | */ | |
158 | if (!same_thread_group(req->task, current) || !in_task()) | |
159 | return false; | |
160 | return true; | |
161 | } | |
162 | #else | |
163 | static bool io_resubmit_prep(struct io_kiocb *req) | |
164 | { | |
165 | return false; | |
166 | } | |
167 | static bool io_rw_should_reissue(struct io_kiocb *req) | |
168 | { | |
169 | return false; | |
170 | } | |
171 | #endif | |
172 | ||
173 | static void kiocb_end_write(struct io_kiocb *req) | |
174 | { | |
175 | /* | |
176 | * Tell lockdep we inherited freeze protection from submission | |
177 | * thread. | |
178 | */ | |
179 | if (req->flags & REQ_F_ISREG) { | |
180 | struct super_block *sb = file_inode(req->file)->i_sb; | |
181 | ||
182 | __sb_writers_acquired(sb, SB_FREEZE_WRITE); | |
183 | sb_end_write(sb); | |
184 | } | |
185 | } | |
186 | ||
187 | static bool __io_complete_rw_common(struct io_kiocb *req, long res) | |
188 | { | |
f2ccb5ae | 189 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
f3b44f92 JA |
190 | |
191 | if (rw->kiocb.ki_flags & IOCB_WRITE) { | |
192 | kiocb_end_write(req); | |
193 | fsnotify_modify(req->file); | |
194 | } else { | |
195 | fsnotify_access(req->file); | |
196 | } | |
197 | if (unlikely(res != req->cqe.res)) { | |
198 | if ((res == -EAGAIN || res == -EOPNOTSUPP) && | |
199 | io_rw_should_reissue(req)) { | |
200 | req->flags |= REQ_F_REISSUE | REQ_F_PARTIAL_IO; | |
201 | return true; | |
202 | } | |
203 | req_set_fail(req); | |
204 | req->cqe.res = res; | |
205 | } | |
206 | return false; | |
207 | } | |
208 | ||
f3b44f92 JA |
209 | static void io_complete_rw(struct kiocb *kiocb, long res) |
210 | { | |
211 | struct io_rw *rw = container_of(kiocb, struct io_rw, kiocb); | |
212 | struct io_kiocb *req = cmd_to_io_kiocb(rw); | |
213 | ||
214 | if (__io_complete_rw_common(req, res)) | |
215 | return; | |
216 | io_req_set_res(req, res, 0); | |
217 | req->io_task_work.func = io_req_task_complete; | |
ed5ccb3b | 218 | io_req_task_work_add(req); |
f3b44f92 JA |
219 | } |
220 | ||
221 | static void io_complete_rw_iopoll(struct kiocb *kiocb, long res) | |
222 | { | |
223 | struct io_rw *rw = container_of(kiocb, struct io_rw, kiocb); | |
224 | struct io_kiocb *req = cmd_to_io_kiocb(rw); | |
225 | ||
226 | if (kiocb->ki_flags & IOCB_WRITE) | |
227 | kiocb_end_write(req); | |
228 | if (unlikely(res != req->cqe.res)) { | |
229 | if (res == -EAGAIN && io_rw_should_reissue(req)) { | |
230 | req->flags |= REQ_F_REISSUE | REQ_F_PARTIAL_IO; | |
231 | return; | |
232 | } | |
233 | req->cqe.res = res; | |
234 | } | |
235 | ||
236 | /* order with io_iopoll_complete() checking ->iopoll_completed */ | |
237 | smp_store_release(&req->iopoll_completed, 1); | |
238 | } | |
239 | ||
df9830d8 | 240 | static int kiocb_done(struct io_kiocb *req, ssize_t ret, |
f3b44f92 JA |
241 | unsigned int issue_flags) |
242 | { | |
243 | struct io_async_rw *io = req->async_data; | |
f2ccb5ae | 244 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
f3b44f92 JA |
245 | |
246 | /* add previously done IO, if any */ | |
247 | if (req_has_async_data(req) && io->bytes_done > 0) { | |
248 | if (ret < 0) | |
249 | ret = io->bytes_done; | |
250 | else | |
251 | ret += io->bytes_done; | |
252 | } | |
253 | ||
254 | if (req->flags & REQ_F_CUR_POS) | |
255 | req->file->f_pos = rw->kiocb.ki_pos; | |
df9830d8 PB |
256 | if (ret >= 0 && (rw->kiocb.ki_complete == io_complete_rw)) { |
257 | if (!__io_complete_rw_common(req, ret)) { | |
258 | io_req_set_res(req, req->cqe.res, | |
259 | io_put_kbuf(req, issue_flags)); | |
260 | return IOU_OK; | |
261 | } | |
262 | } else { | |
f3b44f92 | 263 | io_rw_done(&rw->kiocb, ret); |
df9830d8 | 264 | } |
f3b44f92 JA |
265 | |
266 | if (req->flags & REQ_F_REISSUE) { | |
267 | req->flags &= ~REQ_F_REISSUE; | |
268 | if (io_resubmit_prep(req)) | |
269 | io_req_task_queue_reissue(req); | |
270 | else | |
271 | io_req_task_queue_fail(req, ret); | |
272 | } | |
df9830d8 | 273 | return IOU_ISSUE_SKIP_COMPLETE; |
f3b44f92 JA |
274 | } |
275 | ||
f3b44f92 JA |
276 | #ifdef CONFIG_COMPAT |
277 | static ssize_t io_compat_import(struct io_kiocb *req, struct iovec *iov, | |
278 | unsigned int issue_flags) | |
279 | { | |
f2ccb5ae | 280 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
f3b44f92 JA |
281 | struct compat_iovec __user *uiov; |
282 | compat_ssize_t clen; | |
283 | void __user *buf; | |
284 | size_t len; | |
285 | ||
286 | uiov = u64_to_user_ptr(rw->addr); | |
287 | if (!access_ok(uiov, sizeof(*uiov))) | |
288 | return -EFAULT; | |
289 | if (__get_user(clen, &uiov->iov_len)) | |
290 | return -EFAULT; | |
291 | if (clen < 0) | |
292 | return -EINVAL; | |
293 | ||
294 | len = clen; | |
295 | buf = io_buffer_select(req, &len, issue_flags); | |
296 | if (!buf) | |
297 | return -ENOBUFS; | |
298 | rw->addr = (unsigned long) buf; | |
299 | iov[0].iov_base = buf; | |
300 | rw->len = iov[0].iov_len = (compat_size_t) len; | |
301 | return 0; | |
302 | } | |
303 | #endif | |
304 | ||
305 | static ssize_t __io_iov_buffer_select(struct io_kiocb *req, struct iovec *iov, | |
306 | unsigned int issue_flags) | |
307 | { | |
f2ccb5ae | 308 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
f3b44f92 JA |
309 | struct iovec __user *uiov = u64_to_user_ptr(rw->addr); |
310 | void __user *buf; | |
311 | ssize_t len; | |
312 | ||
313 | if (copy_from_user(iov, uiov, sizeof(*uiov))) | |
314 | return -EFAULT; | |
315 | ||
316 | len = iov[0].iov_len; | |
317 | if (len < 0) | |
318 | return -EINVAL; | |
319 | buf = io_buffer_select(req, &len, issue_flags); | |
320 | if (!buf) | |
321 | return -ENOBUFS; | |
322 | rw->addr = (unsigned long) buf; | |
323 | iov[0].iov_base = buf; | |
324 | rw->len = iov[0].iov_len = len; | |
325 | return 0; | |
326 | } | |
327 | ||
328 | static ssize_t io_iov_buffer_select(struct io_kiocb *req, struct iovec *iov, | |
329 | unsigned int issue_flags) | |
330 | { | |
f2ccb5ae | 331 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
f3b44f92 JA |
332 | |
333 | if (req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)) { | |
334 | iov[0].iov_base = u64_to_user_ptr(rw->addr); | |
335 | iov[0].iov_len = rw->len; | |
336 | return 0; | |
337 | } | |
338 | if (rw->len != 1) | |
339 | return -EINVAL; | |
340 | ||
341 | #ifdef CONFIG_COMPAT | |
342 | if (req->ctx->compat) | |
343 | return io_compat_import(req, iov, issue_flags); | |
344 | #endif | |
345 | ||
346 | return __io_iov_buffer_select(req, iov, issue_flags); | |
347 | } | |
348 | ||
349 | static struct iovec *__io_import_iovec(int ddir, struct io_kiocb *req, | |
350 | struct io_rw_state *s, | |
351 | unsigned int issue_flags) | |
352 | { | |
f2ccb5ae | 353 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
f3b44f92 JA |
354 | struct iov_iter *iter = &s->iter; |
355 | u8 opcode = req->opcode; | |
356 | struct iovec *iovec; | |
357 | void __user *buf; | |
358 | size_t sqe_len; | |
359 | ssize_t ret; | |
360 | ||
361 | if (opcode == IORING_OP_READ_FIXED || opcode == IORING_OP_WRITE_FIXED) { | |
f337a84d | 362 | ret = io_import_fixed(ddir, iter, req->imu, rw->addr, rw->len); |
f3b44f92 JA |
363 | if (ret) |
364 | return ERR_PTR(ret); | |
365 | return NULL; | |
366 | } | |
367 | ||
368 | buf = u64_to_user_ptr(rw->addr); | |
369 | sqe_len = rw->len; | |
370 | ||
371 | if (opcode == IORING_OP_READ || opcode == IORING_OP_WRITE) { | |
372 | if (io_do_buffer_select(req)) { | |
373 | buf = io_buffer_select(req, &sqe_len, issue_flags); | |
374 | if (!buf) | |
375 | return ERR_PTR(-ENOBUFS); | |
376 | rw->addr = (unsigned long) buf; | |
377 | rw->len = sqe_len; | |
378 | } | |
379 | ||
380 | ret = import_single_range(ddir, buf, sqe_len, s->fast_iov, iter); | |
381 | if (ret) | |
382 | return ERR_PTR(ret); | |
383 | return NULL; | |
384 | } | |
385 | ||
386 | iovec = s->fast_iov; | |
387 | if (req->flags & REQ_F_BUFFER_SELECT) { | |
388 | ret = io_iov_buffer_select(req, iovec, issue_flags); | |
389 | if (ret) | |
390 | return ERR_PTR(ret); | |
391 | iov_iter_init(iter, ddir, iovec, 1, iovec->iov_len); | |
392 | return NULL; | |
393 | } | |
394 | ||
395 | ret = __import_iovec(ddir, buf, sqe_len, UIO_FASTIOV, &iovec, iter, | |
396 | req->ctx->compat); | |
397 | if (unlikely(ret < 0)) | |
398 | return ERR_PTR(ret); | |
399 | return iovec; | |
400 | } | |
401 | ||
402 | static inline int io_import_iovec(int rw, struct io_kiocb *req, | |
403 | struct iovec **iovec, struct io_rw_state *s, | |
404 | unsigned int issue_flags) | |
405 | { | |
406 | *iovec = __io_import_iovec(rw, req, s, issue_flags); | |
407 | if (unlikely(IS_ERR(*iovec))) | |
408 | return PTR_ERR(*iovec); | |
409 | ||
410 | iov_iter_save_state(&s->iter, &s->iter_state); | |
411 | return 0; | |
412 | } | |
413 | ||
414 | static inline loff_t *io_kiocb_ppos(struct kiocb *kiocb) | |
415 | { | |
416 | return (kiocb->ki_filp->f_mode & FMODE_STREAM) ? NULL : &kiocb->ki_pos; | |
417 | } | |
418 | ||
419 | /* | |
420 | * For files that don't have ->read_iter() and ->write_iter(), handle them | |
421 | * by looping over ->read() or ->write() manually. | |
422 | */ | |
423 | static ssize_t loop_rw_iter(int ddir, struct io_rw *rw, struct iov_iter *iter) | |
424 | { | |
425 | struct kiocb *kiocb = &rw->kiocb; | |
426 | struct file *file = kiocb->ki_filp; | |
427 | ssize_t ret = 0; | |
428 | loff_t *ppos; | |
429 | ||
430 | /* | |
431 | * Don't support polled IO through this interface, and we can't | |
432 | * support non-blocking either. For the latter, this just causes | |
433 | * the kiocb to be handled from an async context. | |
434 | */ | |
435 | if (kiocb->ki_flags & IOCB_HIPRI) | |
436 | return -EOPNOTSUPP; | |
437 | if ((kiocb->ki_flags & IOCB_NOWAIT) && | |
438 | !(kiocb->ki_filp->f_flags & O_NONBLOCK)) | |
439 | return -EAGAIN; | |
440 | ||
441 | ppos = io_kiocb_ppos(kiocb); | |
442 | ||
443 | while (iov_iter_count(iter)) { | |
444 | struct iovec iovec; | |
445 | ssize_t nr; | |
446 | ||
447 | if (!iov_iter_is_bvec(iter)) { | |
448 | iovec = iov_iter_iovec(iter); | |
449 | } else { | |
450 | iovec.iov_base = u64_to_user_ptr(rw->addr); | |
451 | iovec.iov_len = rw->len; | |
452 | } | |
453 | ||
454 | if (ddir == READ) { | |
455 | nr = file->f_op->read(file, iovec.iov_base, | |
456 | iovec.iov_len, ppos); | |
457 | } else { | |
458 | nr = file->f_op->write(file, iovec.iov_base, | |
459 | iovec.iov_len, ppos); | |
460 | } | |
461 | ||
462 | if (nr < 0) { | |
463 | if (!ret) | |
464 | ret = nr; | |
465 | break; | |
466 | } | |
467 | ret += nr; | |
468 | if (!iov_iter_is_bvec(iter)) { | |
469 | iov_iter_advance(iter, nr); | |
470 | } else { | |
471 | rw->addr += nr; | |
472 | rw->len -= nr; | |
473 | if (!rw->len) | |
474 | break; | |
475 | } | |
476 | if (nr != iovec.iov_len) | |
477 | break; | |
478 | } | |
479 | ||
480 | return ret; | |
481 | } | |
482 | ||
483 | static void io_req_map_rw(struct io_kiocb *req, const struct iovec *iovec, | |
484 | const struct iovec *fast_iov, struct iov_iter *iter) | |
485 | { | |
486 | struct io_async_rw *io = req->async_data; | |
487 | ||
488 | memcpy(&io->s.iter, iter, sizeof(*iter)); | |
489 | io->free_iovec = iovec; | |
490 | io->bytes_done = 0; | |
491 | /* can only be fixed buffers, no need to do anything */ | |
492 | if (iov_iter_is_bvec(iter)) | |
493 | return; | |
494 | if (!iovec) { | |
495 | unsigned iov_off = 0; | |
496 | ||
497 | io->s.iter.iov = io->s.fast_iov; | |
498 | if (iter->iov != fast_iov) { | |
499 | iov_off = iter->iov - fast_iov; | |
500 | io->s.iter.iov += iov_off; | |
501 | } | |
502 | if (io->s.fast_iov != fast_iov) | |
503 | memcpy(io->s.fast_iov + iov_off, fast_iov + iov_off, | |
504 | sizeof(struct iovec) * iter->nr_segs); | |
505 | } else { | |
506 | req->flags |= REQ_F_NEED_CLEANUP; | |
507 | } | |
508 | } | |
509 | ||
510 | static int io_setup_async_rw(struct io_kiocb *req, const struct iovec *iovec, | |
511 | struct io_rw_state *s, bool force) | |
512 | { | |
513 | if (!force && !io_op_defs[req->opcode].prep_async) | |
514 | return 0; | |
515 | if (!req_has_async_data(req)) { | |
516 | struct io_async_rw *iorw; | |
517 | ||
518 | if (io_alloc_async_data(req)) { | |
519 | kfree(iovec); | |
520 | return -ENOMEM; | |
521 | } | |
522 | ||
523 | io_req_map_rw(req, iovec, s->fast_iov, &s->iter); | |
524 | iorw = req->async_data; | |
525 | /* we've copied and mapped the iter, ensure state is saved */ | |
526 | iov_iter_save_state(&iorw->s.iter, &iorw->s.iter_state); | |
527 | } | |
528 | return 0; | |
529 | } | |
530 | ||
531 | static inline int io_rw_prep_async(struct io_kiocb *req, int rw) | |
532 | { | |
533 | struct io_async_rw *iorw = req->async_data; | |
534 | struct iovec *iov; | |
535 | int ret; | |
536 | ||
537 | /* submission path, ->uring_lock should already be taken */ | |
538 | ret = io_import_iovec(rw, req, &iov, &iorw->s, 0); | |
539 | if (unlikely(ret < 0)) | |
540 | return ret; | |
541 | ||
542 | iorw->bytes_done = 0; | |
543 | iorw->free_iovec = iov; | |
544 | if (iov) | |
545 | req->flags |= REQ_F_NEED_CLEANUP; | |
546 | return 0; | |
547 | } | |
548 | ||
549 | int io_readv_prep_async(struct io_kiocb *req) | |
550 | { | |
551 | return io_rw_prep_async(req, READ); | |
552 | } | |
553 | ||
554 | int io_writev_prep_async(struct io_kiocb *req) | |
555 | { | |
556 | return io_rw_prep_async(req, WRITE); | |
557 | } | |
558 | ||
559 | /* | |
560 | * This is our waitqueue callback handler, registered through __folio_lock_async() | |
561 | * when we initially tried to do the IO with the iocb armed our waitqueue. | |
562 | * This gets called when the page is unlocked, and we generally expect that to | |
563 | * happen when the page IO is completed and the page is now uptodate. This will | |
564 | * queue a task_work based retry of the operation, attempting to copy the data | |
565 | * again. If the latter fails because the page was NOT uptodate, then we will | |
566 | * do a thread based blocking retry of the operation. That's the unexpected | |
567 | * slow path. | |
568 | */ | |
569 | static int io_async_buf_func(struct wait_queue_entry *wait, unsigned mode, | |
570 | int sync, void *arg) | |
571 | { | |
572 | struct wait_page_queue *wpq; | |
573 | struct io_kiocb *req = wait->private; | |
f2ccb5ae | 574 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
f3b44f92 JA |
575 | struct wait_page_key *key = arg; |
576 | ||
577 | wpq = container_of(wait, struct wait_page_queue, wait); | |
578 | ||
579 | if (!wake_page_match(wpq, key)) | |
580 | return 0; | |
581 | ||
582 | rw->kiocb.ki_flags &= ~IOCB_WAITQ; | |
583 | list_del_init(&wait->entry); | |
584 | io_req_task_queue(req); | |
585 | return 1; | |
586 | } | |
587 | ||
588 | /* | |
589 | * This controls whether a given IO request should be armed for async page | |
590 | * based retry. If we return false here, the request is handed to the async | |
591 | * worker threads for retry. If we're doing buffered reads on a regular file, | |
592 | * we prepare a private wait_page_queue entry and retry the operation. This | |
593 | * will either succeed because the page is now uptodate and unlocked, or it | |
594 | * will register a callback when the page is unlocked at IO completion. Through | |
595 | * that callback, io_uring uses task_work to setup a retry of the operation. | |
596 | * That retry will attempt the buffered read again. The retry will generally | |
597 | * succeed, or in rare cases where it fails, we then fall back to using the | |
598 | * async worker threads for a blocking retry. | |
599 | */ | |
600 | static bool io_rw_should_retry(struct io_kiocb *req) | |
601 | { | |
602 | struct io_async_rw *io = req->async_data; | |
603 | struct wait_page_queue *wait = &io->wpq; | |
f2ccb5ae | 604 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
f3b44f92 JA |
605 | struct kiocb *kiocb = &rw->kiocb; |
606 | ||
607 | /* never retry for NOWAIT, we just complete with -EAGAIN */ | |
608 | if (req->flags & REQ_F_NOWAIT) | |
609 | return false; | |
610 | ||
611 | /* Only for buffered IO */ | |
612 | if (kiocb->ki_flags & (IOCB_DIRECT | IOCB_HIPRI)) | |
613 | return false; | |
614 | ||
615 | /* | |
616 | * just use poll if we can, and don't attempt if the fs doesn't | |
617 | * support callback based unlocks | |
618 | */ | |
619 | if (file_can_poll(req->file) || !(req->file->f_mode & FMODE_BUF_RASYNC)) | |
620 | return false; | |
621 | ||
622 | wait->wait.func = io_async_buf_func; | |
623 | wait->wait.private = req; | |
624 | wait->wait.flags = 0; | |
625 | INIT_LIST_HEAD(&wait->wait.entry); | |
626 | kiocb->ki_flags |= IOCB_WAITQ; | |
627 | kiocb->ki_flags &= ~IOCB_NOWAIT; | |
628 | kiocb->ki_waitq = wait; | |
629 | return true; | |
630 | } | |
631 | ||
632 | static inline int io_iter_do_read(struct io_rw *rw, struct iov_iter *iter) | |
633 | { | |
634 | struct file *file = rw->kiocb.ki_filp; | |
635 | ||
636 | if (likely(file->f_op->read_iter)) | |
637 | return call_read_iter(file, &rw->kiocb, iter); | |
638 | else if (file->f_op->read) | |
639 | return loop_rw_iter(READ, rw, iter); | |
640 | else | |
641 | return -EINVAL; | |
642 | } | |
643 | ||
4e17aaab | 644 | static bool need_complete_io(struct io_kiocb *req) |
f3b44f92 JA |
645 | { |
646 | return req->flags & REQ_F_ISREG || | |
647 | S_ISBLK(file_inode(req->file)->i_mode); | |
648 | } | |
649 | ||
f3b44f92 JA |
650 | static int io_rw_init_file(struct io_kiocb *req, fmode_t mode) |
651 | { | |
f2ccb5ae | 652 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
f3b44f92 JA |
653 | struct kiocb *kiocb = &rw->kiocb; |
654 | struct io_ring_ctx *ctx = req->ctx; | |
655 | struct file *file = req->file; | |
656 | int ret; | |
657 | ||
658 | if (unlikely(!file || !(file->f_mode & mode))) | |
659 | return -EBADF; | |
660 | ||
661 | if (!io_req_ffs_set(req)) | |
662 | req->flags |= io_file_get_flags(file) << REQ_F_SUPPORT_NOWAIT_BIT; | |
663 | ||
5264406c | 664 | kiocb->ki_flags = file->f_iocb_flags; |
f3b44f92 JA |
665 | ret = kiocb_set_rw_flags(kiocb, rw->flags); |
666 | if (unlikely(ret)) | |
667 | return ret; | |
668 | ||
669 | /* | |
670 | * If the file is marked O_NONBLOCK, still allow retry for it if it | |
671 | * supports async. Otherwise it's impossible to use O_NONBLOCK files | |
672 | * reliably. If not, or it IOCB_NOWAIT is set, don't retry. | |
673 | */ | |
674 | if ((kiocb->ki_flags & IOCB_NOWAIT) || | |
675 | ((file->f_flags & O_NONBLOCK) && !io_file_supports_nowait(req))) | |
676 | req->flags |= REQ_F_NOWAIT; | |
677 | ||
678 | if (ctx->flags & IORING_SETUP_IOPOLL) { | |
679 | if (!(kiocb->ki_flags & IOCB_DIRECT) || !file->f_op->iopoll) | |
680 | return -EOPNOTSUPP; | |
681 | ||
682 | kiocb->private = NULL; | |
683 | kiocb->ki_flags |= IOCB_HIPRI | IOCB_ALLOC_CACHE; | |
684 | kiocb->ki_complete = io_complete_rw_iopoll; | |
685 | req->iopoll_completed = 0; | |
686 | } else { | |
687 | if (kiocb->ki_flags & IOCB_HIPRI) | |
688 | return -EINVAL; | |
689 | kiocb->ki_complete = io_complete_rw; | |
690 | } | |
691 | ||
692 | return 0; | |
693 | } | |
694 | ||
695 | int io_read(struct io_kiocb *req, unsigned int issue_flags) | |
696 | { | |
f2ccb5ae | 697 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
f3b44f92 JA |
698 | struct io_rw_state __s, *s = &__s; |
699 | struct iovec *iovec; | |
700 | struct kiocb *kiocb = &rw->kiocb; | |
701 | bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK; | |
702 | struct io_async_rw *io; | |
703 | ssize_t ret, ret2; | |
704 | loff_t *ppos; | |
705 | ||
706 | if (!req_has_async_data(req)) { | |
707 | ret = io_import_iovec(READ, req, &iovec, s, issue_flags); | |
708 | if (unlikely(ret < 0)) | |
709 | return ret; | |
710 | } else { | |
711 | io = req->async_data; | |
712 | s = &io->s; | |
713 | ||
714 | /* | |
715 | * Safe and required to re-import if we're using provided | |
716 | * buffers, as we dropped the selected one before retry. | |
717 | */ | |
718 | if (io_do_buffer_select(req)) { | |
719 | ret = io_import_iovec(READ, req, &iovec, s, issue_flags); | |
720 | if (unlikely(ret < 0)) | |
721 | return ret; | |
722 | } | |
723 | ||
724 | /* | |
725 | * We come here from an earlier attempt, restore our state to | |
726 | * match in case it doesn't. It's cheap enough that we don't | |
727 | * need to make this conditional. | |
728 | */ | |
729 | iov_iter_restore(&s->iter, &s->iter_state); | |
730 | iovec = NULL; | |
731 | } | |
732 | ret = io_rw_init_file(req, FMODE_READ); | |
733 | if (unlikely(ret)) { | |
734 | kfree(iovec); | |
735 | return ret; | |
736 | } | |
737 | req->cqe.res = iov_iter_count(&s->iter); | |
738 | ||
739 | if (force_nonblock) { | |
740 | /* If the file doesn't support async, just async punt */ | |
741 | if (unlikely(!io_file_supports_nowait(req))) { | |
742 | ret = io_setup_async_rw(req, iovec, s, true); | |
743 | return ret ?: -EAGAIN; | |
744 | } | |
745 | kiocb->ki_flags |= IOCB_NOWAIT; | |
746 | } else { | |
747 | /* Ensure we clear previously set non-block flag */ | |
748 | kiocb->ki_flags &= ~IOCB_NOWAIT; | |
749 | } | |
750 | ||
751 | ppos = io_kiocb_update_pos(req); | |
752 | ||
753 | ret = rw_verify_area(READ, req->file, ppos, req->cqe.res); | |
754 | if (unlikely(ret)) { | |
755 | kfree(iovec); | |
756 | return ret; | |
757 | } | |
758 | ||
759 | ret = io_iter_do_read(rw, &s->iter); | |
760 | ||
761 | if (ret == -EAGAIN || (req->flags & REQ_F_REISSUE)) { | |
762 | req->flags &= ~REQ_F_REISSUE; | |
763 | /* if we can poll, just do that */ | |
764 | if (req->opcode == IORING_OP_READ && file_can_poll(req->file)) | |
765 | return -EAGAIN; | |
766 | /* IOPOLL retry should happen for io-wq threads */ | |
767 | if (!force_nonblock && !(req->ctx->flags & IORING_SETUP_IOPOLL)) | |
768 | goto done; | |
769 | /* no retry on NONBLOCK nor RWF_NOWAIT */ | |
770 | if (req->flags & REQ_F_NOWAIT) | |
771 | goto done; | |
772 | ret = 0; | |
773 | } else if (ret == -EIOCBQUEUED) { | |
df9830d8 PB |
774 | if (iovec) |
775 | kfree(iovec); | |
776 | return IOU_ISSUE_SKIP_COMPLETE; | |
f3b44f92 | 777 | } else if (ret == req->cqe.res || ret <= 0 || !force_nonblock || |
4e17aaab | 778 | (req->flags & REQ_F_NOWAIT) || !need_complete_io(req)) { |
f3b44f92 JA |
779 | /* read all, failed, already did sync or don't want to retry */ |
780 | goto done; | |
781 | } | |
782 | ||
783 | /* | |
784 | * Don't depend on the iter state matching what was consumed, or being | |
785 | * untouched in case of error. Restore it and we'll advance it | |
786 | * manually if we need to. | |
787 | */ | |
788 | iov_iter_restore(&s->iter, &s->iter_state); | |
789 | ||
790 | ret2 = io_setup_async_rw(req, iovec, s, true); | |
791 | if (ret2) | |
792 | return ret2; | |
793 | ||
794 | iovec = NULL; | |
795 | io = req->async_data; | |
796 | s = &io->s; | |
797 | /* | |
798 | * Now use our persistent iterator and state, if we aren't already. | |
799 | * We've restored and mapped the iter to match. | |
800 | */ | |
801 | ||
802 | do { | |
803 | /* | |
804 | * We end up here because of a partial read, either from | |
805 | * above or inside this loop. Advance the iter by the bytes | |
806 | * that were consumed. | |
807 | */ | |
808 | iov_iter_advance(&s->iter, ret); | |
809 | if (!iov_iter_count(&s->iter)) | |
810 | break; | |
811 | io->bytes_done += ret; | |
812 | iov_iter_save_state(&s->iter, &s->iter_state); | |
813 | ||
814 | /* if we can retry, do so with the callbacks armed */ | |
815 | if (!io_rw_should_retry(req)) { | |
816 | kiocb->ki_flags &= ~IOCB_WAITQ; | |
817 | return -EAGAIN; | |
818 | } | |
819 | ||
820 | /* | |
821 | * Now retry read with the IOCB_WAITQ parts set in the iocb. If | |
822 | * we get -EIOCBQUEUED, then we'll get a notification when the | |
823 | * desired page gets unlocked. We can also get a partial read | |
824 | * here, and if we do, then just retry at the new offset. | |
825 | */ | |
826 | ret = io_iter_do_read(rw, &s->iter); | |
827 | if (ret == -EIOCBQUEUED) | |
828 | return IOU_ISSUE_SKIP_COMPLETE; | |
829 | /* we got some bytes, but not all. retry. */ | |
830 | kiocb->ki_flags &= ~IOCB_WAITQ; | |
831 | iov_iter_restore(&s->iter, &s->iter_state); | |
832 | } while (ret > 0); | |
833 | done: | |
f3b44f92 JA |
834 | /* it's faster to check here then delegate to kfree */ |
835 | if (iovec) | |
836 | kfree(iovec); | |
df9830d8 | 837 | return kiocb_done(req, ret, issue_flags); |
f3b44f92 JA |
838 | } |
839 | ||
840 | int io_write(struct io_kiocb *req, unsigned int issue_flags) | |
841 | { | |
f2ccb5ae | 842 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
f3b44f92 JA |
843 | struct io_rw_state __s, *s = &__s; |
844 | struct iovec *iovec; | |
845 | struct kiocb *kiocb = &rw->kiocb; | |
846 | bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK; | |
847 | ssize_t ret, ret2; | |
848 | loff_t *ppos; | |
849 | ||
850 | if (!req_has_async_data(req)) { | |
851 | ret = io_import_iovec(WRITE, req, &iovec, s, issue_flags); | |
852 | if (unlikely(ret < 0)) | |
853 | return ret; | |
854 | } else { | |
855 | struct io_async_rw *io = req->async_data; | |
856 | ||
857 | s = &io->s; | |
858 | iov_iter_restore(&s->iter, &s->iter_state); | |
859 | iovec = NULL; | |
860 | } | |
861 | ret = io_rw_init_file(req, FMODE_WRITE); | |
862 | if (unlikely(ret)) { | |
863 | kfree(iovec); | |
864 | return ret; | |
865 | } | |
866 | req->cqe.res = iov_iter_count(&s->iter); | |
867 | ||
868 | if (force_nonblock) { | |
869 | /* If the file doesn't support async, just async punt */ | |
870 | if (unlikely(!io_file_supports_nowait(req))) | |
871 | goto copy_iov; | |
872 | ||
4e17aaab SR |
873 | /* File path supports NOWAIT for non-direct_IO only for block devices. */ |
874 | if (!(kiocb->ki_flags & IOCB_DIRECT) && | |
875 | !(kiocb->ki_filp->f_mode & FMODE_BUF_WASYNC) && | |
876 | (req->flags & REQ_F_ISREG)) | |
f3b44f92 JA |
877 | goto copy_iov; |
878 | ||
879 | kiocb->ki_flags |= IOCB_NOWAIT; | |
880 | } else { | |
881 | /* Ensure we clear previously set non-block flag */ | |
882 | kiocb->ki_flags &= ~IOCB_NOWAIT; | |
883 | } | |
884 | ||
885 | ppos = io_kiocb_update_pos(req); | |
886 | ||
887 | ret = rw_verify_area(WRITE, req->file, ppos, req->cqe.res); | |
df9830d8 PB |
888 | if (unlikely(ret)) { |
889 | kfree(iovec); | |
890 | return ret; | |
891 | } | |
f3b44f92 JA |
892 | |
893 | /* | |
894 | * Open-code file_start_write here to grab freeze protection, | |
895 | * which will be released by another thread in | |
896 | * io_complete_rw(). Fool lockdep by telling it the lock got | |
897 | * released so that it doesn't complain about the held lock when | |
898 | * we return to userspace. | |
899 | */ | |
900 | if (req->flags & REQ_F_ISREG) { | |
901 | sb_start_write(file_inode(req->file)->i_sb); | |
902 | __sb_writers_release(file_inode(req->file)->i_sb, | |
903 | SB_FREEZE_WRITE); | |
904 | } | |
905 | kiocb->ki_flags |= IOCB_WRITE; | |
906 | ||
907 | if (likely(req->file->f_op->write_iter)) | |
908 | ret2 = call_write_iter(req->file, kiocb, &s->iter); | |
909 | else if (req->file->f_op->write) | |
910 | ret2 = loop_rw_iter(WRITE, rw, &s->iter); | |
911 | else | |
912 | ret2 = -EINVAL; | |
913 | ||
914 | if (req->flags & REQ_F_REISSUE) { | |
915 | req->flags &= ~REQ_F_REISSUE; | |
916 | ret2 = -EAGAIN; | |
917 | } | |
918 | ||
919 | /* | |
920 | * Raw bdev writes will return -EOPNOTSUPP for IOCB_NOWAIT. Just | |
921 | * retry them without IOCB_NOWAIT. | |
922 | */ | |
923 | if (ret2 == -EOPNOTSUPP && (kiocb->ki_flags & IOCB_NOWAIT)) | |
924 | ret2 = -EAGAIN; | |
925 | /* no retry on NONBLOCK nor RWF_NOWAIT */ | |
926 | if (ret2 == -EAGAIN && (req->flags & REQ_F_NOWAIT)) | |
927 | goto done; | |
928 | if (!force_nonblock || ret2 != -EAGAIN) { | |
929 | /* IOPOLL retry should happen for io-wq threads */ | |
930 | if (ret2 == -EAGAIN && (req->ctx->flags & IORING_SETUP_IOPOLL)) | |
931 | goto copy_iov; | |
4e17aaab SR |
932 | |
933 | if (ret2 != req->cqe.res && ret2 >= 0 && need_complete_io(req)) { | |
934 | struct io_async_rw *rw; | |
935 | ||
1c849b48 SR |
936 | trace_io_uring_short_write(req->ctx, kiocb->ki_pos - ret2, |
937 | req->cqe.res, ret2); | |
938 | ||
4e17aaab SR |
939 | /* This is a partial write. The file pos has already been |
940 | * updated, setup the async struct to complete the request | |
941 | * in the worker. Also update bytes_done to account for | |
942 | * the bytes already written. | |
943 | */ | |
944 | iov_iter_save_state(&s->iter, &s->iter_state); | |
945 | ret = io_setup_async_rw(req, iovec, s, true); | |
946 | ||
947 | rw = req->async_data; | |
948 | if (rw) | |
949 | rw->bytes_done += ret2; | |
950 | ||
e053aaf4 JA |
951 | if (kiocb->ki_flags & IOCB_WRITE) |
952 | kiocb_end_write(req); | |
4e17aaab SR |
953 | return ret ? ret : -EAGAIN; |
954 | } | |
f3b44f92 | 955 | done: |
df9830d8 | 956 | ret = kiocb_done(req, ret2, issue_flags); |
f3b44f92 JA |
957 | } else { |
958 | copy_iov: | |
959 | iov_iter_restore(&s->iter, &s->iter_state); | |
960 | ret = io_setup_async_rw(req, iovec, s, false); | |
e053aaf4 JA |
961 | if (!ret) { |
962 | if (kiocb->ki_flags & IOCB_WRITE) | |
963 | kiocb_end_write(req); | |
964 | return -EAGAIN; | |
965 | } | |
966 | return ret; | |
f3b44f92 | 967 | } |
f3b44f92 JA |
968 | /* it's reportedly faster than delegating the null check to kfree() */ |
969 | if (iovec) | |
970 | kfree(iovec); | |
971 | return ret; | |
972 | } | |
973 | ||
974 | static void io_cqring_ev_posted_iopoll(struct io_ring_ctx *ctx) | |
975 | { | |
46929b08 | 976 | io_commit_cqring_flush(ctx); |
f3b44f92 JA |
977 | if (ctx->flags & IORING_SETUP_SQPOLL) |
978 | io_cqring_wake(ctx); | |
979 | } | |
980 | ||
981 | int io_do_iopoll(struct io_ring_ctx *ctx, bool force_nonspin) | |
982 | { | |
983 | struct io_wq_work_node *pos, *start, *prev; | |
984 | unsigned int poll_flags = BLK_POLL_NOSLEEP; | |
985 | DEFINE_IO_COMP_BATCH(iob); | |
986 | int nr_events = 0; | |
987 | ||
988 | /* | |
989 | * Only spin for completions if we don't have multiple devices hanging | |
990 | * off our complete list. | |
991 | */ | |
992 | if (ctx->poll_multi_queue || force_nonspin) | |
993 | poll_flags |= BLK_POLL_ONESHOT; | |
994 | ||
995 | wq_list_for_each(pos, start, &ctx->iopoll_list) { | |
996 | struct io_kiocb *req = container_of(pos, struct io_kiocb, comp_list); | |
f2ccb5ae | 997 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
f3b44f92 JA |
998 | int ret; |
999 | ||
1000 | /* | |
1001 | * Move completed and retryable entries to our local lists. | |
1002 | * If we find a request that requires polling, break out | |
1003 | * and complete those lists first, if we have entries there. | |
1004 | */ | |
1005 | if (READ_ONCE(req->iopoll_completed)) | |
1006 | break; | |
1007 | ||
1008 | ret = rw->kiocb.ki_filp->f_op->iopoll(&rw->kiocb, &iob, poll_flags); | |
1009 | if (unlikely(ret < 0)) | |
1010 | return ret; | |
1011 | else if (ret) | |
1012 | poll_flags |= BLK_POLL_ONESHOT; | |
1013 | ||
1014 | /* iopoll may have completed current req */ | |
1015 | if (!rq_list_empty(iob.req_list) || | |
1016 | READ_ONCE(req->iopoll_completed)) | |
1017 | break; | |
1018 | } | |
1019 | ||
1020 | if (!rq_list_empty(iob.req_list)) | |
1021 | iob.complete(&iob); | |
1022 | else if (!pos) | |
1023 | return 0; | |
1024 | ||
1025 | prev = start; | |
1026 | wq_list_for_each_resume(pos, prev) { | |
1027 | struct io_kiocb *req = container_of(pos, struct io_kiocb, comp_list); | |
1028 | ||
1029 | /* order with io_complete_rw_iopoll(), e.g. ->result updates */ | |
1030 | if (!smp_load_acquire(&req->iopoll_completed)) | |
1031 | break; | |
1032 | nr_events++; | |
1033 | if (unlikely(req->flags & REQ_F_CQE_SKIP)) | |
1034 | continue; | |
1035 | ||
1036 | req->cqe.flags = io_put_kbuf(req, 0); | |
1037 | __io_fill_cqe_req(req->ctx, req); | |
1038 | } | |
1039 | ||
1040 | if (unlikely(!nr_events)) | |
1041 | return 0; | |
1042 | ||
1043 | io_commit_cqring(ctx); | |
1044 | io_cqring_ev_posted_iopoll(ctx); | |
1045 | pos = start ? start->next : ctx->iopoll_list.first; | |
1046 | wq_list_cut(&ctx->iopoll_list, prev, start); | |
1047 | io_free_batch_list(ctx, pos); | |
1048 | return nr_events; | |
1049 | } |